The internet-radio company announced this week that mobile devices will be limited to 40 hours of listening per month, in an attempt to keep down rising royalty costs.

About 75% of Pandora’s streams go to “mobile and other non-traditional devices.”

Online streaming from traditional computers will not be affected by the new monthly limit.

Pandora imposed a similar 40 hour cap in July 2009, though it affected all computers and mobile devices. That limit was raised in 2011.

Only about 4% of Pandora’s users are expected to be affected by the new limits. They will be notified when the 40 hour point is reached, and can pay an additional $0.99 to continue listening until the end of the month.